Inhibition study of human placental aromatase with 3-deoxy- and 6-oxo-steroids using [1β-3H]16α-hydroxyandrostenedione as a substrate : a comparison to that using [1β-3H]androstenedione

• Published in: The Journal of steroid biochemistry and molecular biology Vol. 44; no. 2; pp. 199 - 201
• Main Authors: NUMAZAWA, M, MUTSUMI, A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Science 01.02.1993
• Subjects: Analytical, structural and metabolic biochemistry; Androstenedione - analogs & derivatives; Androstenedione - metabolism; Aromatase Inhibitors; Biological and medical sciences; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Humans; Oxidoreductases; Placenta - enzymology; Steroids - chemistry; Steroids - pharmacology; Substrate Specificity; Human; Steroid; Fetal membrane; Enzyme; Steroid hormone; Enzyme inhibitor; Placenta; Enzymatic activity; Substrate specificity; Steroidogenesis; Oestrogen synthase; Inhibition; Androstenedione
• DOI: 10.1016/0960-0760(93)90028-U
• ISSN: 0960-0760

Inhibition of aromatase activity in human placental microsomes with 3-deoxy- (1, 2, 4, 6 and 8), 6-oxo- (3, 5 and 9), and 16 alpha-bromo- (7) steroids was studied using [1 beta-3H]16 alpha-hydroxyandrostenedione (16 alpha-OHAD) as a substrate and compared to that with the conventional substrate, [1 beta-3H]androstenedione. All the steroids inhibited both 16 alpha-OHAD and [1 beta-3H]androstenedione aromatization in a competitive manner. Based on Ki/Km ratios obtained in both series of experiments, their relative inhibitory activities in the series with 16 alpha-OHAD were not necessarily identical with those in the other series. The results would be important to understand the relationship of structure to function of aromatase in human placental microsomes.